wmaker: remove one level of pointers for the function SlideWindows
The function does not need to be passed a array of pointer to windows
because it does not change content of the pointers. It is more efficient to
directly use an array of windows as the parameter, and simpler also.
As 'SlideWindow' is also concerned, it can be simplified and turned into
an inlinable function so the compiler can optimise it.
Took opportunity to de-CamelCase the name of the functions to comply with
the project's coding style.
Signed-off-by: Christophe CURIS <christophe.curis@free.fr>